change overlay scrollbar hover show to hover fade in

cc/trees/layer_tree_host_impl_unittest.cc

Index: cc/trees/layer_tree_host_impl_unittest.cc
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index e2bf3d4f797e1980dc0d1881cf32043736274d48..8b2802704f73dc20743a2f77aee902e895e3311c 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -2874,6 +2874,7 @@ class LayerTreeHostImplTestScrollbarAnimation : public LayerTreeHostImplTest {
     settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(20);
     settings.scrollbar_fade_out_resize_delay =
         base::TimeDelta::FromMilliseconds(20);
+    settings.scrollbar_fade_in_duration = base::TimeDelta::FromMilliseconds(20);
     settings.scrollbar_fade_out_duration =
         base::TimeDelta::FromMilliseconds(20);
 
@@ -3096,6 +3097,7 @@ class LayerTreeHostImplTestScrollbarOpacity : public LayerTreeHostImplTest {
     settings.scrollbar_animator = animator;
     settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(20);
     settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(20);
+    settings.scrollbar_fade_in_duration = base::TimeDelta::FromMilliseconds(20);
     settings.scrollbar_fade_out_duration =
         base::TimeDelta::FromMilliseconds(20);
     gfx::Size content_size(100, 100);
@@ -3195,6 +3197,7 @@ TEST_F(LayerTreeHostImplTest, ScrollbarVisibilityChangeCausesRedrawAndCommit) {
   settings.scrollbar_animator = LayerTreeSettings::AURA_OVERLAY;
   settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(20);
   settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(20);
+  settings.scrollbar_fade_in_duration = base::TimeDelta::FromMilliseconds(20);
   settings.scrollbar_fade_out_duration = base::TimeDelta::FromMilliseconds(20);
   gfx::Size content_size(100, 100);
 
@@ -3293,6 +3296,7 @@ TEST_F(LayerTreeHostImplTest, ScrollbarRegistration) {
   settings.scrollbar_animator = LayerTreeSettings::ANDROID_OVERLAY;
   settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(20);
   settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(20);
+  settings.scrollbar_fade_in_duration = base::TimeDelta::FromMilliseconds(20);
   settings.scrollbar_fade_out_duration = base::TimeDelta::FromMilliseconds(20);
   CreateHostImpl(settings, CreateCompositorFrameSink());
 
@@ -3415,6 +3419,7 @@ void LayerTreeHostImplTest::SetupMouseMoveAtWithDeviceScale(
   LayerTreeSettings settings = DefaultSettings();
   settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(500);
   settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(500);
+  settings.scrollbar_fade_in_duration = base::TimeDelta::FromMilliseconds(500);
   settings.scrollbar_fade_out_duration = base::TimeDelta::FromMilliseconds(300);
   settings.scrollbar_animator = LayerTreeSettings::AURA_OVERLAY;
 
@@ -12034,6 +12039,7 @@ void LayerTreeHostImplTest::SetupMouseMoveAtTestScrollbarStates(
   LayerTreeSettings settings = DefaultSettings();
   settings.scrollbar_show_delay = base::TimeDelta::FromMilliseconds(500);
   settings.scrollbar_fade_out_delay = base::TimeDelta::FromMilliseconds(500);
+  settings.scrollbar_fade_in_duration = base::TimeDelta::FromMilliseconds(500);
   settings.scrollbar_fade_out_duration = base::TimeDelta::FromMilliseconds(300);
   settings.scrollbar_animator = LayerTreeSettings::AURA_OVERLAY;